Micrometer



sept 12 1967 A. MlNcuzzx 3,340,616

f' 4 5a 27 T/g-VQ 25 B y *JMJ A Horne ys Sept. 12, 1967 A. MlNcuzzl3,340,616

MIGROMETER Filed May 13, 1965 2 Sheets-Sheet 2 Attorneys United StatesPatent O 3,340,616 MICROMETER Antonio Mincuzzi, Milan, Italy, assignorto Soc. per

Azioni Fratelli Borletti, Milan, Italy, an Italian company Filed May 13,1965, Ser. No. 455,428 Claims priority, application Italy, May 13, 1964,10,444/ 64, Patent 47,148 7 Claims. (Cl. 33-166) The manufacture ofmicrometers, particularly those of the -Palmer type, variousarrangements have hitherto been adopted for enabling the scale to beread quickly and with high accuracy. For this purpose, there have inparticular been proposed micrometers having counting mechanisms.

The control of the counting mechanism, the position of which on themicrometer is determined solely by reasons of design, is effected via agear train driven by the rotary member that controls the micrometricscrew of the calibrating rod.

In one construction of more practical interest the counting mechanism,which is generally constituted by a series of flanged rings carrying thenumber on their outer surfaces, is located coaxially with theCalibrating rod, which therefore passes through the said rings.

A construction of this type, which is of particular interest in view ofits simplicity as regards construction, operation and adjustment, isprovided in accordance with the present invention. This constructioncomprises the feature that the Calibrating rod, an extension of which isprovided with the micrometric screwthread, is capable of rot-atingrelative to a nut xed to the body of the micrometer, by means of auniversal joint controlled by a rotatable sleeve. The importance of thesaid universal joint, the operation of which will be describedhereinafter, is

particularly noticeable in large scale or mass production,

where it is possible that during assembly the axis of rotation of thecalibarting rod and the axis of rotation of the control sleeve may notcome perfectly into coincidence. In this case the universal jointnevertheless permits perfect transmission of motion from the controlsleeve to the calibrating rod.

The following description with reference to the accompanying drawings,which illustrate a preferred embodiment of the invention, discloses themain features and the advantage of such a micrometer.

In the drawings:

FIG. 1 is an external view of a micrometer according to the invention inwhich can be seen the counting mechanism, the circumferentialmicrometric graduation and the locking lever,

FIG. 2 is a longitudinal section, on a larger scale than FIG. 1, of thecontrol assembly for the Calibrating rod,

FIG. 3 is a cross section on the line III-III of FIG. 2,

FIGS. 4 and 5 show a detail of the sliding joint connecting the sleeveand the Calibrating rod, and

FIG. 6 shows a detail of two shells of plastic material that cover thehandle of the micrometer.

The body 1 of the micrometer, which has a handle 2 of arcuate form,includes a cylindrical hollow body portion 3 which is located in linewith an anvil 4 and in which is housed the counting mechanism 5.

A member 7 is rigidly fixed by means of a screwthread 6, to the portion3 so as to form a single piece therewith. The member 7 is extended at 8by a sleeve which is screwthreaded at 9. On the screwthread are Screwedtwo nuts 10, 10 which serve respectively as nut and locking nut whichprovide locating nut means. Between the nut 10 and the shoulder 11 ofthe member 7 is accurately located a bushing 12 which is capable ofturning on the outer surface 13 of the extension 8 without being able tomove 3,340,616 Patented Sept. 12, 1967 ICC axially. The bushing 12'is inturn rigidly xed in the nterior of a control sleeve 14 by means ofscrews 15, hence the sleeve 14 can rotate freely relative to the member7, being guided by the bushing 12, without being able to slide axially.

In the inner part of the end of the sleeve 14 remote from the bushing 12is inserted an inner sleeve 18, this being releasably locked against ashoulder 16 by means of an end cap 17. The sleeve 18 has longitudinalinwardly opening groove 19 the centres of which are on a diametricalplane.

In the two diametrically opposed grooves 19 can slide the ends 20 of twopins 21 with plane parallel faces, lixed in diametrically oppositepositions to a collar 22. The latter is mounted, so as to be capable ofslight oscillation, on the end 23 of the Calibrating rod 24 within thesleeve 14, by means of a locating pin 25 the axis of which is normal tothe common axis of both said pins 2,1.

The assembly constituted by the collar 22, pins 21, and pin 25 forms auniversal joint which can turn slightly about the pin 25 and can alsoundergo slight displacements in the direction of the arrow 26. l

When the sleeve 14 is caused to rotate the universal joint abovementioned also rotates, and this causes the calibrating rod 24 to rotatewith it. The rod 24 has an extension 27 with a micrometric screwthreadwhich engages with the internal screwthread 28 in the extension 8, andwhich causes the Calibrating rod 24 to move along its axis, for examplein the direction of the arrow 29. Displacement in the opposite sensewould clearly be elfected by turning the sleeve 14 in the oppositedirection. The Calibrating rod is thus mounted by screwthread 2'8 and byan internal cylindrical bore of member 7, for rotation and laxialsliding movement in and relative to the hollow body.

The end of the extension 8 is slotted at 30 along a diametrical plane,and externally is of sli-ghtly conical shape and is screwthreaded. A nut31 is screwed onto this screwthread to the extent that some play is leftbetween the internal screwthread 28 and the screwthreaded shank of theCalibrating rod.

Rotation of the sleeve 14 is transmitted by means of an internallytoothed wheel 32 to a wheel 33, ya shaft 34, a wheel 35, a wheel 36 (seeFIG. 3) and nally to a wheel 37 fixed to a disc 40 actuating'thecounting mechanism comprising an assembly of numbered rings through atooth 41.

For setting to zero the micrometer the end of the calibrating rod 24 isbrought against the anvil 4; then the cap 17 is unscrewed so that theinner sleeve 18 will be freely rotatable in the respect of the sleeve14, and the sleeve 14 is rotated so that all numbered rings of thecounting mechanism 5 Will be brought to zero, the Calibrating rod beingmaintained fixed.

The cap 17 is now locked again and the phasing of the sleeve 14 in therespect of the counting mechanism 5 is performed through the ring 38having a graduation 46. To this aim the ring 38 will be rotated on thesleeve 14 in the respect of the index 47 ixed to the body 1 and lockedin the zero position through screw dowels 39. The screwthreads on theend cap 17 thus constitute one means for xedly securing the cap onsleeve 14 in a position to bear against sleeve 18 and lock sleeve 1-8against movement relative to sleeve 14.

In a preferred construction the transmission ratio between thesuccessive numbered rings 43, 44 and 45 is such that the iirst ringmakes one rotation for two tenths of a millimetre of movement of theCalibrating rod, the second ring for two millimetres, the third fortwenty millimetres and the fourth for two hundred millimetres. Thelatter however can turn only through two iigures, the extent ofmeasurement of the micrometer being -25 mm.

The ratios and the values indicated by the numbered rings may obviouslybe different from those -above mentioned, and in particular the scalemay be in inches instead of millimetres, without exceeding the scope ofthe invention.

Accuracy of reading is obtained by observing the graduation 46 on thering 3S relative to an index mark 47 xed to the body.

The counting mechanism is mounted in the interior of the cylindricalzone 3 after being assembled on the ringcarrier 48 which is adapted tobe inserted in the cavity in the Zone 3 of the body. The carrier 48,which carries both the numbered rings and the yassociated pinions islocked in this cavity by the end cover 50 which is screwed into positionat 51, via a spring 52 and an interposed sleeve 48 which also serves toprotect the numbers.

The counting mechanism is actuated by means ot one or the other of tworings 53 which draw the sleeve 14 into rotation by friction. Each ring53 has slip friction connection with control sleeve 14 to limit thetorque that can be applied to sleeve 14 by a ring 53. This sleeve inturn operates via the grooves 19 and the pins 21 to effect rotation ofthe calibrating rod 27-24 which, screwing at 2S, is caused to moveaxially until it engages the object to be measured, the object beingplaced between the anvil 4 and the end of the calibrating rod 24. Thepressure with which the calibr-ating rod engages the object to bemeasured depends on the value of the couple that the friction of the tworings 53 is able to transmit to the sleeve 14. This pressure ormeasuring load is preferably of the order of 1 kg.

By means of a handle 54 mounted for rotation on the xed hollow body withan eccentric pin 54 a pin 55 can be shifted axially to lock therelatively rotatable bushing 12 by pressure on its surface, thusenabling the relevant reading to be made without error.

The handle 2 is protected by two shells 56 and 57, preferably made fromplastic material, which are forced onto the curved part of the body,causing at least one projection 58 on one shell to enter a correspondingrecess in the opposing shell.

What I claim is:

1. A counter micrometer comprising a hollow body, a calibrating rod,means mounting the calibrating rod for rotation and axial slidingmovement in and relative to the hollow body, a control sleeve mountedfor rotation on the hollow body, counting mechanism disposed in thehollow body and adapted to be actuated by rotation of said controlsleeve, means defining on the inner side of said control sleeve aninwardly opening groove that extends longitudinally of the controlsleeve, a member extending into said groove and slidable longitudinallyof said groove, and means interconnecting said member Iand saidcalibrating rod for conjoint rotation and for swinging movement of saidcalibrating rod and said member relative to each other.

2. A counter micrometer as claimed in claim 1, said means dening saidgroove comprising an inner sleeve disposed within said control sleeve,said inner sleeve having two diametrically opposed said longitudinalgrooves, and said member having two diametrically opposite projectingpins engaging in said grooves.

3. A counter micrometer as claimed in claim 1, said means dening saidgroove comprising an inner sleeve mounted in said control sleeve forrotation of said inner sleeve and said control sleeve relative to eachother about the axis of said sleeves, and means for releasably securingsaid inner sleeve in fixed position relative to said control sleevethereby accurately to set the micrometer,

4. A counter micrometer as claimed in claim 3, said releasably securingmeans comprising an end cap removable to expose said inner sleeve, andmeans for xedly securing said cap on said control sleeve in a positionto bear against said inner sleeve and lock said inner sleeve againstmovement relative to said control sleeve.

5. A counter micrometer comprising a hollow body, a calibrating rod,means mounting the calibrating rod for rotation and axial slidingmovement in and relative to the hollow body, a control sleeve mountedfor rotation on the hollow body, counting mechanism disposed in thehollow body and adapted to be actuated by rotation of said controlsleeve, a ring mounted for rotation on and relative to said controlsleeve, said ring having graduations thereon registrable with a xed markon said hollow body, means for selectively locking said ring on saidcontrol sleeve thereby accurately to set the micrometer, a bushingdisposed within and fixed to the control sleeve, and locating nut meansscrew-threadedly carried by said hollow body, said bushing beingdisposed between said nut means and an annular shoulder on said body andserving to guide the rotation of the control sleeve without play.

6. A counter micrometer comprising a hollow body, a calibrating rod,means mounting the calibrating rod for rotation and axial slidingmovement in and relative to the hollow body, a control sleeve mountedfor rotation on the hollow body, counting mechanism disposed in thehollow body and adapted to be actuated by rotation of said controlsleeve, a ring mounted for rotation on and relative to said controlsleeve, said ring having graduations thereon registrable with a -iixedmar-k on said hollow body, means for selectively locking said ring onsaid control sleeve thereby accurately to set the micrometer, and ahandle on said hollow body, a pair of shells of plastic materialdisposed on opposite sides of said handle, and a projection on one saidshell extending into a recess in the other said shell thereby to holdthe shells together on opposite sides of the handle.

7. A counter micrometer comprising a hollow body, a calibrating rod,means mounting the calibrating rod for rotation and axial slidingmovement in and relative to the hollow body, a control sleeve mountedfor rotation on the hollow body, counting mechanism disposed in thehollow body and adapted to be actuated by rotation of said controlsleeve, la. ring mounted for rotation on and relative to said controlsleeve, said ring having graduations thereon registrable With a lixedmark on said hollow body, means for selectively locking said ring onsaid control sleeve thereby accurately to set the micrometer, andlocking means comprising an eccentric member mounted for rotation on thehollow body and having means adapted to engage between a xed part and arotatable part of the micrometer thereby to tix said parts releasablytogether to enable a correct reading to be made.

References Cited UNITED STATES PATENTS 756,461 4/1904 Borduas 33-1661,107,202 `8/1914 Savage 33-116 1,638,366 8/1927 Sandoz 33-164 1,389,0288/ 1931 Colburn 33-166 2,957,248 10/1960 Stedman et al 33-164 3,120,0612/ 1964 Pfleiderer 33-166 FOREIGN PATENTS 467,023 11/ 1951 Italy.

LEONARD FORMAN, Primary Examiner.

WILLIAM D. MARTIN, Examiner.

1. A COUNTER MICROMETER COMPRISING A HOLLOW BODY, A CALIBRATING ROD,MEANS MOUNTING THE CALIBRATING ROD FOR ROTATION AND AXIAL SLIDINGMOVEMENT IN AND RELATIVE TO THE HOLLOW BODY, A CONTROL SLEEVE MOUNTEDFOR ROTATION ON THE HOLLOW BODY, COUNTING MECHANISM DISPOSED IN THEHOLLOW BODY AND ADAPTED TO BE ACTUATED BY ROTATION OF SAID CONTROLSLEEVE, MEANS DEFINING ON THE INNER SIDE OF SAID CONTROL SLEEVE ANINWARDLY OPENING GROOVE THAT EXTENDS LONGITUDINALLY OF THE CONTROLSLEEVE, A MEMBER EXTENDING INTO SAID GROOVE AND SLIDABLE LONGITUDINALLYOF SAID GROOVE, AND MEANS INTERCONNECTING SAID MEMBER AND SAIDCALIBRATING ROD FOR CONJOINT ROTATION AND FOR SWINGING MOVEMENT OF SAIDCALIBRATING ROD AND SAID MEMBER RELATIVE TO EACH OTHER.